1. Technical Field
Embodiments of the present disclosure relate to telephone link detecting technology, and particularly to a gateway and method for detecting a communication link between a called telephone and a telephone switch.
2. Description of Related Art
Currently, one method for detecting a communication link between a called telephone and a telephone switch includes detecting a capacitance between a positive wire and a negative wire of a telephone line that electrically connects the called telephone with the telephone switch, so as to obtain a ringer equivalency number (REN). If a value of the capacitance is greater than or equal to a preset value, the REN is regarded as one, otherwise, if the value of the capacitance is less than the preset value, the REN is regarded as zero. The method determines that the communication link between the called telephone and the telephone switch has been established if REN is not equal to one, or determines that the communication link between the called telephone and the telephone switch has not been established if REN is equal to zero.
However, sometimes, although the value of the capacitance is less than the preset value, actually, the communication link between the called telephone and the telephone switch has been established (i.e., REN≠0). Therefore, an error detect result will be generated if just determining whether REN is equal to zero or not, thus, a prompt and accurate detecting method is desired.